I am using Chrome on a mac, using Gravity Forms Developer Edition version 1.6.3.2 and the option to enable salesforce is not showing in the advanced area and I installed the latest version of the SF plugin.
I am using the same script files you are (cycle,jQuery, etc.) my experience has always been that script files in conflict is what causes this issue. But same problem for me, but I have a client that requested this plugin, sigh . . .